Cheaper chrono's can have problems with low angle sunshine, and give bad readings on occasion. On the F1 owned, this is mitigated by 2 small cardboard pieces placed in slot directly in front of the "eyes". As far as being "exact", how would you determine the exact velocity to determine that? Uncle Nick would likely know. There are comparison vids to compare various chrono's, and i would likely trust the accuracy of Labradar's readings over a cheaper F1. Alot of how the F1 reads may be influenced by how it is set up each time, but how accurate do you actually need?
https://www.ar15.com/forums/Precisio...in-OP/10-6511/